Crude petroleum oil and other liquids often contain sulphur compounds such as, but not limited to, hydrogen sulphide, mercaptans, thioethers, disulphides, thiophenes, cyclic polymethylene sulphides, and the like. Volatile sulphur species dissolved in the liquids often render the liquids highly toxic and highly odorous. As such, crude petroleum oils and other liquids containing such volatile sulphur species are often difficult or dangerous to handle, transport and store.
Because of their volatility, sulphur species typically collect in the headspace of the oil/liquid storage/transport systems. Direct contact with crude petroleum oil and other liquids containing sulphuric compounds may also be hazardous, as such sulphuric compounds may be absorbed directly from the fluids. Limiting exposure to these chemical compounds during handling is desirable.
There are various techniques used in petroleum refining to remove hydrogen sulphides and mercaptans from organic media. For example, sulphuric species may be removed from crude oil and its derivatives by catalytic hydro-desulfurization or catalytic oxidative desulfurization. However, such removal processes require large industrial installations in order to be employed. In other examples, amine-based scavengers have also been used to manage sulphuric species in organic media. However, such scavengers form by-products that may cause problems in downfield applications of the treated media, such as, but not limited to, oil reforming where reformer catalysts are sensitive to nitrogen content. In addition, amines in crude oil have also been known to distill in crude towers and overhead condensing systems, contributing to salt fouling and related corrosion activity.
Some commercial products only focus on the removal of dissolved hydrogen sulphide content of crude oils and hydrogen sulphide gas present in liquid overheads. As such, these untreated or partially treated liquids often continue to contain other noxious sulphur-containing species (e.g. mercaptans) that have considerable objectionable odours. As sulphur-containing species sometimes have the same or similar odour, odours resulting from the volatilization of other noxious sulphur-containing species may mask the presence of un-removed hydrogen sulphide (which is similarly odorous), thereby leading to potential detrimental effects. Without the aid of chemical testing, it would be difficult to determine if a liquid contaminated with noxious sulphur-containing species (e.g. mercaptans) is also contaminated with the considerably more dangerous hydrogen sulphide.
Mercaptan species may be oxidized by iodine in solution (Kirihara et al. Synthesis, 2007, 21:3286). In addition, iodine may aid in the management of certain sulphur-containing species (e.g. NL 8104616; U.S. Pat. No. 4,224,139). However, iodine is a solid with poor handling and dissolution properties in both oil and water, sublimes at room temperature, and can be hazardous under certain conditions. Most solvents for iodine are volatile alcohols that are flammable, and certain solvents would be susceptible to oxidative attack by the oxidizing agent used.